Ok, my environment is working again. Unfortunately I cannot tell you specifically what the issue was, but here are the steps and the versions I now have.

Steps

Started xCode - The update to 9.3 had been auto update installed a couple of days prior, but I had not actually started it since that update. I noticed that on starting xCode it seems to have some installation steps to complete. My guess is completing those installs from the xCode update was the cause.

Restarted OSX

Updated to XDE 2.24.3

NOT DONE - Mac OS High Sierra 10.13.4 Update - I had not yet installed the 10.13.4 update. But will do that shortly and confirm it doesn’t break anything